Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 23
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Molecules ; 29(9)2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38731598

RESUMO

Obtaining high-added value compounds from agricultural waste receives increasing attention, as it can both improve resource utilization efficiency and reduce waste generation. In this study, polysaccharides are extracted from the discarded roots of Abelmoschus manihot (L.) by the high-efficiency ultrasound-assisted extraction (UAE). The optimized condition was determined as solid-liquid ratio SL ratio = 1:20, temperature T = 30 °C and time T = 40 min, achieving an extraction yield of 13.41%. Composition analysis revealed that glucose (Glc, 44.65%), rhamnose (Rha, 26.30%), galacturonic acid (GalA, 12.50%) and galactose (Gal, 9.86%) are the major monosaccharides of the extract. The extract showed a low degree of esterification (DE) value of 40.95%, and its Fourier-transform infrared (FT-IR) spectrum exhibited several characteristic peaks of polysaccharides. Inspired by the wide cosmetic applications of polysaccharides, the skincare effect of the extract was evaluated via the moisture retention, total phenolic content (TPC) quantification, 2,2-Diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging activity, anti-hyaluronidase and anti-elastase activity experiments. The extract solutions demonstrated a 48 h moisture retention rate of 10.75%, which is superior to that of commercially available moisturizer hyaluronic acid (HA). Moreover, both the TPC value of 16.16 mg GAE/g (dw) and DPPH-free radical scavenging activity of 89.20% at the concentration of 2 mg/mL indicated the strong anti-oxidant properties of the extract. Furthermore, the anti-hyaluronidase activity and moderate anti-elastase activity were determined as 72.16% and 42.02%, respectively. In general, in vitro skincare effect experiments suggest moisturizing, anti-oxidant, anti-radical and anti-aging activities of the A. manihot root extract, indicating its potential applications in the cosmetic industry.


Assuntos
Abelmoschus , Antioxidantes , Extratos Vegetais , Raízes de Plantas , Polissacarídeos , Polissacarídeos/química , Polissacarídeos/farmacologia , Polissacarídeos/isolamento & purificação , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Raízes de Plantas/química , Abelmoschus/química , Antioxidantes/química , Antioxidantes/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Higiene da Pele/métodos , Ramnose/química , Galactose , Ácidos Hexurônicos/química , Fenóis/química , Fenóis/análise , Fenóis/farmacologia , Humanos
2.
Front Bioeng Biotechnol ; 12: 1276795, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38449677

RESUMO

Dynamic assessment of cerebral blood flow (CBF) is crucial for guiding personalized management and treatment strategies, and improving the prognosis of stroke. However, a safe, reliable, and effective method for dynamic CBF evaluation is currently lacking in clinical practice. In this study, we developed a CBF monitoring system utilizing electromagnetic coupling sensing (ECS). This system detects variations in brain conductivity and dielectric constant by identifying the resonant frequency (RF) in an equivalent circuit containing both magnetic induction and electrical coupling. We evaluated the performance of the system using a self-made physical model of blood vessel pulsation to test pulsatile CBF. Additionally, we recruited 29 healthy volunteers to monitor cerebral oxygen (CO), cerebral blood flow velocity (CBFV) data and RF data before and after caffeine consumption. We analyzed RF and CBFV trends during immediate responses to abnormal intracranial blood supply, induced by changes in vascular stiffness, and compared them with CO data. Furthermore, we explored a method of dynamically assessing the overall level of CBF by leveraging image feature analysis. Experimental testing substantiates that this system provides a detection range and depth enhanced by three to four times compared to conventional electromagnetic detection techniques, thereby comprehensively covering the principal intracranial blood supply areas. And the system effectively captures CBF responses under different intravascular pressure stimulations. In healthy volunteers, as cerebral vascular stiffness increases and CO decreases due to caffeine intake, the RF pulsation amplitude diminishes progressively. Upon extraction and selection of image features, widely used machine learning algorithms exhibit commendable performance in classifying overall CBF levels. These results highlight that our proposed methodology, predicated on ECS and image feature analysis, enables the capture of immediate responses of abnormal intracranial blood supply triggered by alterations in vascular stiffness. Moreover, it provides an accurate diagnosis of the overall CBF level under varying physiological conditions.

3.
Heliyon ; 10(4): e26245, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38434095

RESUMO

Measuring industrial eco-efficiency (IEE) is essential to improve environmental quality and industrial restructuring. However, most studies ignore the influence of embeddedness on industrial eco-efficiency and lack analysis of the pathways of influence factors. Therefore, this study assesses industrial eco-efficiency in the Yellow River Basin (YRB) using a super-efficiency model slacks-based measure (Super-SBM) that considers non-desired outputs, outlines the social embeddedness of IEE, and empirically analyzes the driving mechanism of IEE from the perspective of embeddedness by constructing hierarchical linear modeling (HLM) to address the pathways of action of the influencing factors of industrial eco-efficiency. The results showed that 50.79% of the overall differences in IEE in the YRB were caused by social embeddedness. Economic development level, industrial agglomeration, and environmental regulation (ER) are significant direct influencing factors. Increasing cognitive and cultural embeddedness will enhance the positive relationship between economic development level and IEE. Political and relational embeddedness significantly moderates the positive relationship between industrial agglomeration and eco-efficiency. Cultural embeddedness can significantly and directly affect industrial eco-efficiency and weaken the positive relationship between ERs and industrial eco-efficiency. Therefore, improving IEE should consider both fundamental and embedded factors. Our findings are conducive to promoting high-quality development in the YRB and support the government in formulating differentiated policies. In addition, this paper tries to establish an empirical analysis method suitable for social embeddedness theory, and the empirical results help to improve the situation due to the lack of empirical analysis of social embeddedness theory.

4.
J Environ Manage ; 357: 120713, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38552520

RESUMO

With the continuous advancement of urban renewal, the application of recycled aggregates (RA) is a win-win measure to solve the treatment of construction waste and provide the required building materials. However, the existence of a large amount of old adhesive mortar (OAM) makes it difficult for RA to equivalently replace natural aggregates (NA) due to their higher water absorption and crushing index, as well as a lower apparent density. From the published literature on enhancing RA, the most mature and easiest method for construction is physical enhancement technology. Therefore, through a review of recent related researches, this article summarizes and compares the modification effects of mechanical grinding technology, traditional heating and grinding technology, and microwave heating technology on the physical properties of RA, including water absorption, apparent density, and crushing value. The related modification mechanisms were discussed. Additionally, the impacts of different physical enhancement technologies on the environment and economy effects are assessed from the perspectives of carbon emissions and cost required during processing. Based on multi-criteria analysis, microwave heating technology is more efficient and cleaner, which is the most recommended in the future.


Assuntos
Resíduos Industriais , Reciclagem , Resíduos Industriais/análise , Reciclagem/métodos , Materiais de Construção , Água , Desempenho Físico Funcional
5.
Med Phys ; 51(2): 1460-1473, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37757449

RESUMO

BACKGROUND: Seed implant brachytherapy (SIBT) is an effective treatment modality for head and neck (H&N) cancers; however, current clinical planning requires manual setting of needle paths and utilizes inaccurate dose calculation algorithms. PURPOSE: This study aims to develop an accurate and efficient deep convolutional neural network dose engine (DCNN-DE) and an automatic SIBT planning method for H&N SIBT. METHODS: A cohort of 25 H&N patients who received SIBT was utilized to develop and validate the methods. The DCNN-DE was developed based on 3D-unet model. It takes single seed dose distribution from a modified TG-43 method, the CT image and a novel inter-seed shadow map (ISSM) as inputs, and predicts the dose map of accuracy close to the one from Monte Carlo simulations (MCS). The ISSM was proposed to better handle inter-seed attenuation. The accuracy and efficacy of the DCNN-DE were validated by comparing with other methods taking MCS dose as reference. For SIBT planning, a novel strategy inspired by clinical practice was proposed to automatically generate parallel or non-parallel potential needle paths that avoid puncturing bone and critical organs. A heuristic-based optimization method was developed to optimize the seed positions to meet clinical prescription requirements. The proposed planning method was validated by re-planning the 25 cases and comparing with clinical plans. RESULTS: The absolute percentage error in the TG-43 calculation for CTV V100 and D90 was reduced from 5.4% and 13.2% to 0.4% and 1.1% with DCNN-DE, an accuracy improvement of 93% and 92%, respectively. The proposed planning method could automatically obtain a plan in 2.5 ± 1.5 min. The generated plans were judged clinically acceptable with dose distribution comparable with those of the clinical plans. CONCLUSIONS: The proposed method can generate clinically acceptable plans quickly with high accuracy in dose evaluation, and thus has a high potential for clinical use in SIBT.


Assuntos
Braquiterapia , Neoplasias de Cabeça e Pescoço , Humanos , Braquiterapia/métodos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Redes Neurais de Computação , Algoritmos , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/radioterapia , Método de Monte Carlo
6.
Angew Chem Int Ed Engl ; 62(50): e202313753, 2023 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-37899303

RESUMO

The abnormality in the glycosylation of surface proteins is critical for the growth and metastasis of tumors and their capacity for immunosuppression and drug resistance. This anomaly offers an entry point for real-time analysis on glycosylation fluctuations. In this study, we report a strategy, glycan metabolic fluorine labeling (MEFLA), for selectively tagging glycans of tumor cells. As a proof of concept, we synthesized two fluorinated unnatural monosaccharides with distinctive 19 F chemical shifts (Ac4 ManNTfe and Ac4 GalNTfa). These two probes could undergo selective uptake by tumor cells and subsequent incorporation into surface glycans. This approach enables efficient and specific 19 F labeling of tumor cells, which permits in vivo tracking of tumor cells and in situ assessment of glycosylation changes by 19 F MRI. The efficiency and specificity of our probes for labeling tumor cells were verified in vitro with A549 cells. The feasibility of our method was further validated with in vivo experiments on A549 tumor-bearing mice. Moreover, the capacity of our approach for assessing glycosylation changes of tumor cells was illustrated both in vitro and in vivo. Our studies provide a promising means for visualizing tumor cells in vivo and assessing their glycosylation variations in situ through targeted multiplexed 19 F MRI.


Assuntos
Flúor , Monossacarídeos , Animais , Camundongos , Glicosilação , Monossacarídeos/metabolismo , Polissacarídeos/metabolismo
7.
Front Public Health ; 11: 1126569, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37808982

RESUMO

Background: As a primary source of added sugars in the US diet, sugar-sweetened beverage (SSB) consumption is presumed to contribute to obesity prevalence and poor oral health. We systematically synthesized and quantified evidence from US-based natural experiments concerning the impact of SSB taxes on beverage prices, sales, purchases, and consumption. Methods: A keyword and reference search was performed in PubMed, Web of Science, Cochrane Library, Scopus, and EconLit from the inception of an electronic bibliographic database to Oct 31, 2022. Meta-analysis was conducted to estimate the pooled effect of soda taxes on SSB consumption, prices, passthrough rate, and purchases. Results: Twenty-six natural experiments, all adopting a difference-in-differences approach, were included. Studies assessed soda taxes in Berkeley, Oakland, and San Francisco in California, Philadelphia in Pennsylvania, Boulder in Colorado, Seattle in Washington, and Cook County in Illinois. Tax rates ranged from 1 to 2 ¢/oz. The imposition of the soda tax was associated with a 1.06 ¢/oz. (95% confidence interval [CI] = 0.90, 1.22) increase in SSB prices and a 27.3% (95% CI = 19.3, 35.4%) decrease in SSB purchases. The soda tax passthrough rate was 79.7% (95% CI = 65.8, 93.6%). A 1 ¢/oz. increase in soda tax rate was associated with increased prices of SSBs by 0.84 ¢/oz (95% CI = 0.33, 1.35). Conclusion: Soda taxes could be effective policy leverage to nudge people toward purchasing and consuming fewer SSBs. Future research should examine evidence-based classifications of SSBs, targeted use of revenues generated by taxes to reduce health and income disparities, and the feasibility of redesigning the soda tax to improve efficiency.


Assuntos
Bebidas Gaseificadas , Impostos , Humanos , Comportamento do Consumidor , Bebidas , Dieta
8.
BMC Public Health ; 23(1): 1361, 2023 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-37454041

RESUMO

BACKGROUND: High fasting plasma glucose (HFPG) is the fastest-growing risk factor for cancer deaths worldwide. We reported the cancer mortality attributable to HFPG at global, regional, and national levels over the past three decades and associations with age, period, and birth cohort. METHODS: Data for this study were retrieved from the Global Burden of Disease Study 2019, and we used age-period-cohort modelling to estimate age, cohort and period effects, as well as net drift (overall annual percentage change) and local drift (annual percentage change in each age group). RESULTS: Over the past 30 years, the global age-standardized mortality rate (ASMR) attributable to HFPG has increased by 27.8%. The ASMR in 2019 was highest in the male population in high sociodemographic index (SDI) areas (8.70; 95% CI, 2.23-18.04). The net drift for mortality was highest in the female population in low SDI areas (2.33; 95% CI, 2.12-2.55). Unfavourable period and cohort effects were found across all SDI quintiles. Cancer subtypes such as "trachea, bronchus, and lung cancers", "colon and rectal cancers", "breast cancer" and "pancreatic cancer" exhibited similar trends. CONCLUSIONS: The cancer mortality attributable to HFPG has surged during the past three decades. Unfavourable age-period-cohort effects on mortality were observed across all SDI quintiles, and the cancer mortality attributable to HFPG is expected to continue to increase rapidly in the future, particularly in lower SDI locations. This is a grim global public health issue that requires immediate attention.


Assuntos
Glicemia , Neoplasias , Humanos , Masculino , Feminino , Anos de Vida Ajustados por Qualidade de Vida , Carga Global da Doença , Fatores de Risco , Saúde Global , Jejum , Estudos de Coortes
9.
Front Neurosci ; 17: 1173127, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37065908

RESUMO

This study aimed to investigate the eye movement characteristics and visual fatigue of virtual reality games with different interaction modes. Eye movement data were recorded using the built-in eye tracker of the VR device and eye movement parameters were calculated from the recorded raw data. The Visual Fatigue Scales and Simulator Sickness Questionnaire were used to subjectively assess visual fatigue and overall discomfort of the VR experience. Sixteen male and 17 female students were recruited for this study. Results showed that both the primary and 360 mode of VR could cause visual fatigue after 30 min of gameplay, with significant differences observed in eye movement behavior between the two modes. The primary mode was more likely to cause visual fatigue, as shown by objective measurements of blinking and pupil diameter. Fixation and saccade parameters also showed significant differences between the two modes, possibly due to the different interaction modes employed in the 360 mode. Further research is required to examine the effects of different content and interactive modes of VR on visual fatigue, as well as to develop more objective measures for assessing it.

10.
Front Physiol ; 13: 899830, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35957987

RESUMO

Spaceflight presents a series of physiological and pathological challenges to astronauts resulting from ionizing radiation, microgravity, isolation, and other spaceflight hazards. These risks cause a series of aging-related diseases associated with increased oxidative stress and mitochondria dysfunction. The skin contains many autofluorescent substances, such as nicotinamide adenine dinucleotide phosphate (NAD(P)H), keratin, melanin, elastin, and collagen, which reflect physiological and pathological changes in vivo. In this study, we used a portable handheld two-photon microscope to conduct high-resolution in vivo skin imaging on volunteers during 15 days of head-down bed rest. The two-photon microscope, equipped with a flexible handheld scanning head, was used to measure two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) images of the left forearm, left front chest, and forehead of volunteers. Changes in TPEF, SHG, and the extended SHG-to-AF(TPEF) aging index of the dermis (SAAID) were measured. It was found that TPEF intensity increased during bed rest and was restored to normal levels after recovery. Meanwhile, SHG increased slightly during bed rest, and the skin aging index increased. Moreover, we found the skin TPEF signals of the left forearm were significantly negatively associated with the oxidative stress marker malondialdehyde (MDA) and DNA damage marker 8-hydroxy-2'-desoxyguanosine (8-OHdG) values of subjects during head-down bed rest. Meanwhile, the SHG signals were also significantly negatively correlated with MDA and 8-OHDG. A significant negative correlation between the extended SAAID of the left chest and serum antioxidant superoxide dismutase (SOD) levels was also found. These results demonstrate that skin autofluorescence signals can reflect changes in human oxidant status. This study provides evidence for in-orbit monitoring of changes in human stress using a portable handheld two-photon microscope for skin imaging.

11.
Comput Intell Neurosci ; 2022: 2850604, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35785100

RESUMO

Based on the risk management of exposure to foreign exchange assets and liabilities and the application of financial derivatives, this paper provides an in-depth analysis of the financial and exchange rate risks of foreign-funded enterprises. Therefore, a method of evaluating the financial performance of listed financial enterprises based on principal component analysis and neural network model is proposed. First, principal components of alternative financial performance input-output indicators are extracted using principal component analysis. Subsequently, these principal components are used as input-output data for the DEA model to derive the relative validity evaluation results of the financial performance of individual financial enterprises and to provide a reference for decision making to improve the financial performance level of financial enterprises. Combined with the economic business data of the enterprises, an empirical test on exchange rate risk management is conducted and relevant suggestions are made on how foreign enterprises can reduce exchange rate risk losses. It has important theoretical value and practical significance for enterprise finance and exchange rate management.


Assuntos
Administração Financeira , Aprendizado de Máquina , Comércio , Redes Neurais de Computação , Análise de Componente Principal
12.
Front Oncol ; 11: 751922, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34868957

RESUMO

PURPOSE: The purpose of this study is to establish and assess a practical delivery quality assurance method for stereotactic radiosurgery with Cyberknife by analyzing the geometric and dosimetric accuracies obtained using a PTW31016 PinPoint ionization chamber and EBT3 films. Moreover, this study also explores the relationship between the parameters of plan complexity, target volume, and deliverability parameters and provides a valuable reference for improving plan optimization and validation. METHODS: One hundred fifty cases of delivery quality assurance plans were performed on Cyberknife to assess point dose and planar dose distribution, respectively, using a PTW31016 PinPoint ionization chamber and Gafchromic EBT3 films. The measured chamber doses were compared with the planned mean doses in the sensitive volume of the chamber, and the measured planar doses were compared with the calculated dose distribution using gamma index analysis. The gamma passing rates were evaluated using the criteria of 3%/1 mm and 2%/2 mm. The statistical significance of the correlations between the complexity metrics, target volume, and the gamma passing rate were analyzed using Spearman's rank correlation coefficient. RESULTS: For point dose comparison, the averaged dose differences (± standard deviations) were 1.6 ± 0.73% for all the cases. For planar dose distribution, the mean gamma passing rate for 3%/1 mm, and 2%/2 mm evaluation criteria were 94.26% ± 1.89%, and 93.86% ± 2.16%, respectively. The gamma passing rates were higher than 90% for all the delivery quality assurance plans with the criteria of 3%/1 mm and 2%/2 mm. The difference in point dose was lowly correlated with volume of PTV, number of beams, and treatment time for 150 DQA plans, and highly correlated with volume of PTV for 18 DQA plans of small target. DQA gamma passing rate (2%/2 mm) was a moderate significant correlation for the number of nodes, number of beams and treatment time, and a low correlation with MU. CONCLUSION: PTW31016 PinPoint ionization chamber and EBT3 film can be used for routine Cyberknife delivery quality assurance. The point dose difference should be within 3%. The gamma passing rate should be higher than 90% for the criteria of 3%/1 mm and 2%/2 mm. In addition, the plan complexity and PTV volume were found to have some influence on the plan deliverability.

13.
Environ Sci Technol ; 55(24): 16757-16769, 2021 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-34855371

RESUMO

Rivers play an important role in the global carbon (C) cycle. However, it remains unknown how long-term river C fluxes change because of climate, land-use, and other environmental changes. Here, we investigated the spatiotemporal variations in global freshwater C cycling in the 20th century using the mechanistic IMAGE-Dynamic Global Nutrient Model extended with the Dynamic In-Stream Chemistry Carbon module (DISC-CARBON) that couples river basin hydrology, environmental conditions, and C delivery with C flows from headwaters to mouths. The results show heterogeneous spatial distribution of dissolved inorganic carbon (DIC) concentrations in global inland waters with the lowest concentrations in the tropics and highest concentrations in the Arctic and semiarid and arid regions. Dissolved organic carbon (DOC) concentrations are less than 10 mg C/L in most global inland waters and are generally high in high-latitude basins. Increasing global C inputs, burial, and CO2 emissions reported in the literature are confirmed by DISC-CARBON. Global river C export to oceans has been stable around 0.9 Pg yr-1. The long-term changes and spatial patterns of concentrations and fluxes of different C forms in the global river network unfold the combined influence of the lithology, climate, and hydrology of river basins, terrestrial and biological C sources, in-stream C transformations, and human interferences such as damming.


Assuntos
Matéria Orgânica Dissolvida , Rios , Regiões Árticas , Água Doce , Humanos , Hidrologia
14.
Cancers (Basel) ; 13(18)2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34572772

RESUMO

Non-small cell lung cancer (NSCLC) is the most common malignancy which requires radiotherapy (RT) as an important part of its multimodality treatment. With the advent of the novel irradiation technique, the clinical outcome of NSCLC patients who receive RT has been dramatically improved. The emergence of proton therapy, which allows for a sharper dose of build-up and drop-off compared to photon therapy, has potentially improved clinical outcomes of NSCLC. Dosimetry studies have indicated that proton therapy can significantly reduce the doses for normal organs, especially the lung, heart, and esophagus while maintaining similar robust target volume coverage in both early and advanced NSCLC compared with photon therapy. However, to date, most studies have been single-arm and concluded no significant changes in the efficacy for early-stage NSCLC by proton therapy over stereotactic body radiation therapy (SBRT). The results of proton therapy for advanced NSCLC in these studies were promising, with improved clinical outcomes and reduced toxicities compared with historical photon therapy data. However, these studies were also mainly single-arm and lacked a direct comparison between the two therapies. Currently, there is much emerging evidence focusing on dosimetry, efficacy, safety, and cost-effectiveness of proton therapy for NSCLC that has been published, however, a comprehensive review comparing these therapies is, to date, lacking. Thus, this review focuses on these aspects of proton therapy for NSCLC.

15.
Sci Total Environ ; 723: 137870, 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32203799

RESUMO

Prefabrication has gained its popularity in countries including China due to its various advantages such as quality control, waste reduction, onsite and offsite parallel coordination, and so on. It has also been recognized as a key strategy to reduce construction-induced carbon emissions. However, there is limited research to examine carbon emission reduction in prefabrication by using the advanced technological artefacts, e.g., building information modeling (BIM), emerging from the technology sphere. As a digital representation of a facility, BIM provides a cyber platform based on which many assessment and simulation works can be performed without having to construct the physical facility. This paper aims to develop a BIM-based approach to measuring carbon emission reduction during the materialization stage of a prefabricated building project. Findings from the study indicate that BIM is an efficient and effective method for measuring carbon emissions from the construction of new buildings and that prefabrication reduces carbon emissions when compared with conventional construction methods. The research contributes to the body of knowledge relating to the reduction of carbon emissions through prefabrication. This is pertinent to contractors, homebuyers and governments who are constantly seeking ways to achieve a circular economy.

16.
Nanomaterials (Basel) ; 10(2)2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-32098041

RESUMO

It is difficult to keep the balance of high quality and high yield for graphene quantum dots (GQDs). Because the quality is uncontrollable during cutting large 2D nanosheets to small 0D nanodots by top-down methods and the yield is low for GQDs with high quality obtained from bottom-up strategy. Here, aphanitic graphite (AG), a low-cost graphite contains a large amount of small graphite nanocrystals with size of about 10 nm is used as the precursor of graphene oxide quantum dots (GO-QDs) for the first time. GO-QDs with high yield and high quality were successfully obtained directly by liquid phase exfoliating AG without high strength cutting. The yield of these GO-QDs can reach up to 40 wt. %, much higher than that obtained from flake graphite (FG) precursor (less than 10 wt. %). The size of GO-QDs can be controlled in 2-10 nm. The average thickness of GO-QDs is about 3 nm, less than 3 layer of graphene sheet. Graphene quantum dots (GQDs) with different surface properties can be easily obtained by simple hydrothermal treatment of GO-QDs, which can be used as highly efficient fluorescent probe. Developing AG as precursor for GQDs offers a way to produce GQDs in a low-cost, highly effective and scalable manner.

17.
Water Res ; 157: 247-257, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30954700

RESUMO

Effluents containing disinfection byproducts (DBPs) from wastewater treatment plants (WWTPs) may be discharged to the receiving water bodies or reused for irrigation, landscaping, and environmental supplies as well as a source to replenish groundwater. Thus the formation and risk of the DBPs in disinfected wastewater effluents should be concerned. In this study, the occurrence of 44 DBPs including 6 trihalomethanes (THMs), 9 haloaceticacids (HAAs), 2 haloketones (HKs), 9 halonitromethanes (HNMs), 9 haloacetonitriles (HANs) and 9 nitrosamines (NAs) was investigated in 12 chlorinated WWTP effluents from five cities of East China. The contribution of each class of DBPs to the total DBPs concentration and additive toxicity was calculated. The average concentrations of the 6 classes of DBPs were ranked as follows: HAAs (47.0 µg/L) > THMs (28.0 µg/L) > HANs (9.9 µg/L) > HNMs (2.9 µg/L) > HKs (0.79 µg/L) > NAs (0.69 µg/L). The significant positive correlations were observed between the formation of THMs and HAAs, THMs and HANs, as well as HAAs and HANs. The results showed that HAAs and THMs were the dominant DBPs on a mass concentration basis and accounted for 54% and 29%, respectively in the total measured DBPs, but they made a minor contribution to the calculated DBP-associated cytotoxicity. HANs and NAs dominated the DBP-associated cytotoxicity, accounting for 50% and 34% on an additive toxicity basis despite the minor contributions to the mass concentration with 10% and 1%, respectively. The risk quotients for three taxonomic groups (fish, daphnid, and green algae) were calculated to assess the ecological risk of DBPs, and the results demonstrated that both HAAs and HANs had high ecological risk for green algae in chlorinated wastewater effluents.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Purificação da Água , China , Desinfecção , Halogenação , Medição de Risco , Trialometanos , Águas Residuárias
18.
Public Health Nutr ; 22(9): 1704-1716, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30834852

RESUMO

OBJECTIVE: Food pantries play a critical role in combating food insecurity. The objective of the present work was to systematically review and synthesize scientific evidence regarding the effectiveness of food pantry-based interventions in the USA. DESIGN: Keyword/reference search was conducted in PubMed, Web of Science, Scopus, Cochrane Library and CINAHL for peer-reviewed articles published until May 2018 that met the following criteria. SETTING: food pantry and/or food bank in the USA; study design: randomized controlled trial (RCT) or pre-post study; outcomes: diet-related outcomes (e.g. nutrition knowledge, food choice, food security, diet quality); study subjects: food pantry/bank clients. RESULTS: Fourteen articles evaluating twelve distinct interventions identified from the keyword/reference search met the eligibility criteria and were included in the review. Five were RCT and the remaining seven were pre-post studies. All studies found that food pantry-based interventions were effective in improving participants' diet-related outcomes. In particular, the nutrition education interventions and the client-choice intervention enhanced participants' nutrition knowledge, cooking skills, food security status and fresh produce intake. The food display intervention helped pantry clients select healthier food items. The diabetes management intervention reduced participants' glycaemic level. CONCLUSIONS: Food pantry-based interventions were found to be effective in improving participants' diet-related outcomes. Interventions were modest in scale and usually short in follow-up duration. Future studies are warranted to address the challenges of conducting interventions in food pantries, such as shortage in personnel and resources, to ensure intervention sustainability and long-term effectiveness.


Assuntos
Assistência Alimentar , Abastecimento de Alimentos , Dieta , Alimentos , Humanos , Estados Unidos
19.
J Appl Clin Med Phys ; 19(3): 142-148, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29603564

RESUMO

Monte Carlo (MC) simulation, as the most accurate dose calculation algorithm, is available in the MultiPlan treatment planning system for Cyberknife. The main purpose of this work was to perform experiments to thoroughly investigate the accuracy of the MC dose calculation algorithm. Besides the basic MC beam commissioning, two test scenarios were designed. First, single beam tests were performed with a solid water phantom to verify the MC source model in simple geometry. Then, a lung treatment plan on a CIRS thorax phantom was created to mimic the clinical patient treatment. The plan was optimized and calculated using ray tracing (RT) algorithm and then recalculated using MC algorithm. Measurements were performed in both a homogeneous phantom and a heterogeneous phantom (CIRS). Ion-chamber and radiochromic film were used to obtain absolute point dose and dose distributions. Ion-chamber results showed that the differences between measured and MC calculated dose were within 3% for all tests. On the film measurements, MC calculation results showed good agreements with the measured dose for all single beam tests. As for the lung case, the gamma passing rate between measured and MC calculated dose was 98.31% and 97.28% for homogeneous and heterogeneous situation, respectively, using 3%/2 mm criteria. However, RT algorithm failed with the passing rate of 79.25% (3%/2 mm) for heterogeneous situation. These results demonstrated that MC dose calculation algorithm in the Multiplan system is accurate enough for patient dose calculation. It is strongly recommended to use MC algorithm in heterogeneous media.


Assuntos
Algoritmos , Método de Monte Carlo , Imagens de Fantasmas , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/normas , Neoplasias Torácicas/cirurgia , Humanos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos
20.
Chin Med J (Engl) ; 130(9): 1093-1099, 2017 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-28469106

RESUMO

BACKGROUND: A novel radioactive 125I seed-loaded biliary stent has been used for patients with malignant biliary obstruction. However, the dosimetric characteristics of the stents remain unclear. Therefore, we aimed to describe the dosimetry of the stents of different lengths - with different number as well as activities of 125I seeds. METHODS: The radiation dosimetry of three representative radioactive stent models was evaluated using a treatment planning system (TPS), thermoluminescent dosimeter (TLD) measurements, and Monte Carlo (MC) simulations. In the process of TPS calculation and TLD measurement, two different water-equivalent phantoms were designed to obtain cumulative radial dose distribution. Calibration procedures using TLD in the designed phantom were also conducted. MC simulations were performed using the Monte Carlo N-Particle eXtended version 2.5 general purpose code to calculate the radioactive stent's three-dimensional dose rate distribution in liquid water. Analysis of covariance was used to examine the factors influencing radial dose distribution of the radioactive stent. RESULTS: The maximum reduction in cumulative radial dose was 26% when the seed activity changed from 0.5 mCi to 0.4 mCi for the same length of radioactive stents. The TLD's dose response in the range of 0-10 mGy irradiation by 137Cs γ-ray was linear: y = 182225x - 6651.9 (R2=0.99152; y is the irradiation dose in mGy, x is the TLDs' reading in nC). When TLDs were irradiated by different energy radiation sources to a dose of 1 mGy, reading of TLDs was different. Doses at a distance of 0.1 cm from the three stents' surface simulated by MC were 79, 93, and 97 Gy. CONCLUSIONS: TPS calculation, TLD measurement, and MC simulation were performed and were found to be in good agreement. Although the whole experiment was conducted in water-equivalent phantom, data in our evaluation may provide a theoretical basis for dosimetry for the clinical application.


Assuntos
Dosimetria Termoluminescente/métodos , Braquiterapia/métodos , Simulação por Computador , Humanos , Método de Monte Carlo , Radiometria/métodos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA